1. Field of the Invention
The present invention relates to an electrophotographic printer, and more particularly, to an electrophotographic printer having a transfer unit with an improved structure.
2. Description of the Related Art
Generally, an electrophotographic printer such as a laser printer or a photocopy machine includes a photosensitive medium such as photosensitive belt on which an electrostatic latent image is formed by an image forming unit. The latent image formed on the photosensitive belt is developed in a developing unit by applying toner thereon.
Then, the developed image is printed on paper via a transfer roller by a transferring unit. The transfer roller is interposed between a backup roller and a pressing roller, and the photosensitive belt travels between the backup roller and the transfer roller, and the paper is provided between the transfer roller and the pressing roller. Thus, the image on the photosensitive belt is transferred onto the transfer roller and then printed on the paper.
Here, during the printing operation, the backup roller, the transfer roller and the pressing roller are adjacent to each other. At times other than the printing operation, the rollers are separated from each other. That is, the transfer roller and the pressing roller are separated from the backup roller, arid then the pressing roller is separated from the transfer roller.
Thus, repeated contact and separation of the three rollers may cause misalignment of the rollers. Also, when the rollers approach each other, vibration may occur due to their contact. In addition, when the vibration is transmitted to the developing unit, an image developing function may be detrimentally affected.